static function duplicateOperationNameMessage($operationName) { return "There can only be one operation named \"{$operationName}\"."; }
private function duplicateOp($opName, $l1, $c1, $l2, $c2) { return FormattedError::create(UniqueOperationNames::duplicateOperationNameMessage($opName), [new SourceLocation($l1, $c1), new SourceLocation($l2, $c2)]); }